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F. F. STARR Oct. 29, 1929.

CARBURETOR Filed Nov. 16, 1925 Patented Oct. 29, 1929 UNITED STATES PATENT? OFFICE FRANK F. STARR, OF DAYTON, OHIO, ASSIGNOR TO DELCO LIGHT COMPANY, OTEDAY- TON, OHIO, A CORPORATION OF DELAWARE CARIBURETOR Application filed November 16, 1925. Serial No. 69,310.

This invention relates to carburetors for internal-combustion engines, and more particularly to the valves for controlling the admission of air to the carburetor.

One of the objects of the invention is to reduce the cost of manufacture of carburetors by simplifying the construction of the air valve mechanism.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the embodiment of the present invention is clearly shown.

In the drawings:

Fig. 1 is a plan view of the carburetor embodying the present invention shown attached to an internal-combustion engine, a fragmentary plan View of which is shown;

Fig. 2 is a sectional view on the line 22 of Fig. 1.

Referring to the drawings, 20 designates the cylinder of an internal-combustion engine to which is attached a cylinder head 21 providing a fuel intake passage 22 which is controlled by a valve 23 in the usual manner. The engine carburetor 24 includes a frame or body 25 which is attached to the cylinder head 21 by bolts 26 and nuts 27. The carburetor body 25 includes an air inlet passage 28 leading through a venturi 29 into a fuel mix ture passage 30 which is in alignment with the passage 22 of the cylinder head 21. Passage of air from the air inlet 28 to the venturi 29 is controlled by an air Valve 31 having a stem 32 guided by a bushing 33 threaded into the upper wall of the body 25. The valve 31 is yieldingly maintained upon its seat by a spring 34. A constantly-open passage for conducting air from the outside to the venturi 29 is provided by a central passage 35 within the Valve stem 32 and by side openings 36 connecting the central passage 35 with the interior of the carburetor body 25.

The liquid fuel is admitted to the carburetor through a passage 40 provided within the carburetor body. Passage 40 communicates with a strainer well 41 closed by a plug 42 and containing a strainer 43. The well 41 is connected with the venturi 29 by a small hole 44.

The lower side of the carburetor body is in the form of a circular boss 50 provided with an annular groove 51 for receiving the upper end of a draft tube 52 which maybe connected with the engine crankcase, so that air and gasoline vapors within the crankcase may be drawn into the carburetor.

The suction of the engine during cranking is sufficient to cause the-valve 31 to be lifted against the spring 34, so that air could be ad mitted to the carburetor through the passage 28 as well as through passages 35 and 36. in order to secure a rich mixture while starting the engine, the operator will press the valve stem 32 downwardly in order to close the valve 31, so that air for combustion is drawn through the passages 35 and 36 oniy. Tn this way, a richer fuel mixture is obtained for starting the engine easily. After the engine becomes self-operative and it is thoroughly warm, the operator may release the stem so that air may be supplied through the passages 28 and 35. v

The fuel mixture proportions will be n ade still richer if the operator presses his finger upon the upper end of the valve stem when pushing the valve stem downwardly, since then no air will be admitted to the carburetor through the passage 35. This should be done especially in cold weather, in order to draw a charge of practically raw fuel into the engine for purposes of priming.

The fuel mixture proportions may be varied by adjusting the bushing 33 into or out of the carburetor body 25. Obviously, if the bushing is screwed out of the body, the initial compression of the spring 34 will be relieved so that the valve 31 will open easier at a given speed and suction. This will cause the mixture to become more lean. Obviously, screwing the bushing 33 into the carburetor body will cause the fuel mixture to become more rich.

It is apparent that the present invention provides an exceedingly simple device for controlling the fuel and air mixture proportions for the purpose of obtaining a rich mixture for starting the engine and for obtaining the most economical mixture for operating the engine under different conditions of temperature or fuel volatility.

WVhile the form of embodiment of the invention as herein disclosed, constitutes a preferred term, it is to be understood that other forms mi ht be adopted, all coming Within the scope of the claims which follow.

W hat is claimed is as follows:

1. A carburetor comprising in combination, a body providing a mixing chamber and a passage for air into the chamber, a valve for controlling the flow of air through said passage, and a manually-operable member for closing the valve, the member having an air passage leading into the chamber, the entrance to the last mentioned passage being located so as to be closed by the hand of the operator When the member is manually operated to close the valve.

2. A carburetor comprising, in combination, a body providing a mixing chamber and a passage for air into the mixing chamber, a valve normally tending to close the passage and adapted to be opened by reduction of pressure Within the chamber, and a manuah ly operated member for positively closing the valve from the exterior of the carburetor, said member having an air 'iassage to said chamber open at all times When the valve is free to operate in response to the pressure in the chamber, and adapted to be closed When said member is operated to close the valve.

3. A carburetor comprising, in combination, a mixing chamber and an air inlet passage, a valve normally tending to close said passage and adapted to open in response to reduction of pressure in said chamber, and a stem for the valve extending through the ex terior of the valve body and provided with an air passage for conducting air into the carburetor, said valve stem passage being open at all times when the valve is free to operate in response to the pressure in the chamber and adapted to be closed When the stem is operated from the exterior of the casing to close the valve.

4:. A carburetor comprising in combination, a body providing a mixing chamber and a passage for air into the chamber, a valve normally tending to close the passage and adapted to open in response to reduction of pressure in the chamber, and a manually operable member for positively closing the valve having an air passage leading into the chamber, said last-mentioned passage being open at all times when the valve is free to operate in response to the pressure in the first mentioned passage, and the entrance to said second passage being located so as to be closed by the hand of the operator when the member is manually operated to close the valve.

In testimony whereof 1 hereto affix my signature.

FRANK F. STARR. 

